Assessment of Doses Received By Premature Babies In Their First Months of Life

Premature babies often need to be treated for respiratory or digestive diseases in neonatal intensive care units. Incidentally, frequent radiological examinations such as chest or abdomen are being performed during their medical follow-up. Furthermore, those patients who have clinical complications may require a complementary period of hospitalisation lasting, in few cases, several months later. Additional X-ray examinations, which often result in higher doses, can also be carried out during this period. With the view of establishing a baseline framework for a possible epidemiological study and in order to assess the potential increased risk among the population of premature babies due to these cumulative exposures, a dosimetric study was carried out in collaboration with both intensive care unit and radiology department of Trousseau Hospital in Paris in 2002. Entrance surface doses were measured by thermoluminescent dosimeters stuck on patient's skin at the centre of the incident beam while radiographs were being taken. In parallel, doses due to other types of examinations were assessed from the X-ray tube parameters. Individual cumulative doses received over the period of stay were estimated, for each premature baby born in 2002, taking into account the number of examinations which they underwent. Results showed that, even if the average dose per radiograph was relatively low (average entrance dose, effective dose and bone marrow dose of 70 μGy, 25 μSv, 6 μSv, respectively), the cumulative dose strongly depended on the length of stay. The average cumulative effective dose was close to 1 mSv. In some extreme cases, characterized by severe health complications and requiring several months of hospitalization, the cumulative effective dose reached about 20 mSv. This work constitutes a preliminary step towards the assessment of the feasibility of an epidemiological study dealing with the premature babies’ population and highlights the need for the optimization of the radiographic techniques and radiation protection for this particular population.